Cursor control assembly

Abstract

An improved ball-type cursor control assembly is provided for controlling the position of a cursor or the like within the field of a video display. The control assembly comprises two orthogonally spaced rotatable traction wheels for supporting the ball at two points substantially at the horizontal equator of the ball and a rolling bearing positioned generally equidistant between the traction wheels to frictionally support the ball at a point substantially below the horizontal ball equator. The traction wheels and rolling bearing thus define three contact points lying within a common plane canted relative to the horizontal ball equator to permit the traction wheels to be positioned to contact the ball substantially at or slightly below said equator. In one preferred form, the traction wheels and rolling bearing are mounted on support brackets upstanding from a support platform having a central opening therein through which a portion of the ball extends thereby permitting the platform to be positioned in a plane less than one ball radius from the horizontal equator of the ball.

What is claimed is: 
     
       1. A ball-type cursor control assembly for controlling the position of a cursor within the field of a video display, comprising: a control ball;   a support platform;   a pair of traction wheels rotatably supported by said support platform at orthogonally spaced positions for contacting and supporting said control ball;   a rolling bearing rotatably supported by said support platform for contacting and supporting said control ball at a side thereof generally opposite said traction wheels and generally equidistant between said traction wheels;   said traction wheels being positioned to contact said control ball at two respective contact points substantially at the horizontal equator of said control ball and said rolling bearing being positioned to contact said control ball at a third contact point substantially below said ball equator whereby said contact points lie in a common plane canted relative to said ball equator and passing below the center of the ball and wherein said contact points lie on a radius substantially less than the radius of said control ball; and   means responsive to rotation of said traction wheels for controlling the position of said cursor within the field of the video display.   
     
     
       2. The cursor control assembly of claim 1 wherein said traction wheels each are relatively narrow in the axial direction and has a substantial diameter on the order of about one-half the ball diameter. 
     
     
       3. The cursor assembly of claim 2 wherein said traction wheels each have a plurality of apertures formed near the periphery thereof. 
     
     
       4. The cursor control assembly of claim 1 wherein said support platform includes a plurality of suppot brackets upstanding integrally therefrom for rotationally supporting said traction wheels and said rolling bearing. 
     
     
       5. The cursor control assembly of claim 4 wherein said support platform has a central opening formed wherein for downward reception therethrough of a portion of said control ball, whereby said support platform is disposed less than one radius of said control ball from the horizontal ball equator. 
     
     
       6. The cursor control assembly of claim 5 including means for mounting said support platform in a plane generally parallel with the horizontal ball equator. 
     
     
       7. The cursor control assembly of claim 6 including a housing, said support platform being mounted within said housing. 
     
     
       8. A ball-type cursor control assembly for controlling the position of a cursor within the field of a video display, comprising: a control ball;   a support platform;   a pair of traction wheels rotatably supported by said support platform at orthogonally spaced positions for contacting and supporting said control ball;   a rolling bearing rotatably supported by said support platform for contacting and supporting said control ball at a side thereof generally opposite said traction wheels and generally equidistant between said traction wheels;   said traction wheels being positioned to contact said control ball at two respective contact points substantially at the horizontal equator of said control ball and said rolling bearing being positioned to contact said control ball at a third contact point substantially below said ball equator whereby said contact points lie in a common plane canted relative to said ball equator and passing below the center of the ball and wherein said contact points lie on a radius substantially less than the radius of said control ball;   said support platform having a central opening formed therein for downward reception therethrough of a portion of said control ball;   means for mounting said support platform in a plane generally below the horizontal ball equator less than one radius of said control ball from the horizontal ball equator; and   means responsive to rotation of said traction wheels for controlling the position of said cursor within the field of the video display.